The research program proposed aims to: (1) establish the extent to which the procarcinogens can be detected as mutagens n Drosophila; (2) explore the nature and capacity of activating enzymes in the system; (3) investigate whether mutagenic response to procarcinogens can be modified by inducers, inhibitors and cofactors of the MFO-system; (4) isolate and characterize mutagen-sensitive mutants and examine their utility for a better identification of carcinogenic aromatics and polycyclic hydrocarbos; (5) study the relationship between chemical reaction pattern and mutagenic properties of alkyating agents; (6) establish the resolving power (and thus the realtive reliability) of different genetic end points used as measure of mutagenicity at toxic and subtoxic concentrations; and finally (7) evaluate the Drosophila results with data obtained in mammalian systems in which the same chemicals have been used. The outcome of this work will be critically evaluated to determine the degree of correlation between carcinogenicity (mutagenicity in mammalian systems) ad mutagenicity in Drosophila.